Electrical switch



Sept. 13, 1938. A. J. KERCHER ELECTRICAL SWITCH Filed Sept. ll, 1955 ATTORNEY.

Patented Sept. 13, 1938 UNITED y STATES PATENT OFFICE 3 Claims.

This invention relates generally to electrical contacting devices or switches adapted to be operated by current ilow, and is intended particularly for use in electrical systems where it is desired to limit the applied current load to a value below that which would be imposed if all of the portions of the system were simultaneously connected to the current supply.

It is an object of the invention to provide an improved switch of the above character, which will afford reliable operation and which can'be readily adjusted in accordance with various requirements.

Further objects of the invention will appear from the following description in which the preferred embodiment of the invention has been set forth in detail in conjunction with the accompanying drawing.

Referring to the drawing:

Fig. l is a cross-sectional detail showing a switch incorporating the present invention.

Fig. 2 is a cross-sectional detail taken along the line 2 2 of Fig. l.

.Fig S is a cross-sectional detail taken along Y, the line 3 3 of Fig. 1.

1Ihe switch II illustrated in the drawing is mounted upon a supporting base or panel I0, to which a suitable cover can be secured. f

Other parts can be carried by base I0, such as a terminal strip I3, terminals 2, and devices such as a magnetic switch controlled by the relay I I.

The relay switch Il includes a pair of field coils i4 and I5, formed from sprally wound ribbon-like conductors I6. The convolutions of each coil are prevented from direct electrical contact with each other, by suitable insulating material Il. The terminals I8 and I9 of coil I4 are shown connected to the terminal connectors 4 and 5. Likewise terminals 2| and 22 of coil I5 are shown connected to the terminal connectors I and 2.

While the coils i4 and i5 are self supporting, suitable means are provided for retaining them spaced in side-by-side relationship, as illustrated in Fig. 2. Thus end plates 23 and 24 are clamped on opposite sides of the coil I4, by screws 26. Likewise end plates 2l and 28 are clamped on opposite sides of the coil I5. Spacers 29 interconnect the plates 24 and 2l, and the assembly of the two coils thus formed, is carried upon the panel i3 by bracket 30.

Extending through the space between the coils I4 and I5 and at right angles to the common magnetic axis, there is a shaft 3|, which carries a laminated magnetic armature 32. One end (Cl. ZOO-100) of shaft 3I is carried by journal 33, while the other end is journaled to the corresponding end of an aligned shaft 36. A bracket 3l serves to support shaft 36, and is in turn mounted upon plate 2l. In order to serve as a bias tending to rotate shaft 3| and armature 32 in one direction, a relatively light spirally formed spring 38 is provided. The inner end of this spring connects to shaft 3l, while the outer end is attached to an arm 39, which in turn is carried by shaft 36. To aiord convenient means for adjusting the angular setting of shaft 36, a shaft 4I is rotatably carried by plate 2l and extends at right angles to the axis of shafts 3I and 36. A portion 42 of this shaft 4i is threaded to form a worm, which is retained in engagement with gear teeth 43 formed on shaft 36. The upper end 44 of shaft #il is slotted or otherwise formed to receive a suitable adjusting tool, such as the bit of a screw driver Upon changing the setting of shaft 4I, it is evident that the angular setting of shaft 36 is altered, to vary the tension of spring 38.

One or more electrical contacts are arranged to be opened and closed, by oscillating movements of shaft 3l and armature 32. Thus, as shown in Fig. 3, a pair of spring arms 46 extend laterally from shaft 3l, and serve to carry movable contacts 4l and 48. These contacts cooperate with relatively stationary contacts 49 and 5I. Contact 5I is carried by a leaf spring 50, for a reason which will be presently explained. As illustrated in Fig. 2, the tension of spring 38 normally tends to rotate armature 32 in a clockwise direction, to maintain contacts 4l and 49 closed, and contacts 48 and 5I open. This position of armature 32 corresponds to a condition at which time little if any current is owing through either of the coils I4 and I5. 1t will be noted that the ends of armature 32 extend into the coils I4 and I5, and that the armature is at an angle between a position substantially parallel to the magnetic axis of the coils, and a position substantially normal to such axis. Sufiicient energization of either one or both of the coils I4 and I5, causes a torque to be applied to the armature 32, in a counter-clockwise direction as viewed in Fig. 2, so that when such current values reach a predetermined maximum, contacts 48 and 5I are closed.

While various methods of winding can be utilized for the coils I4 and I5, the arrangement illustrated in Fig. 3 is desirable. Thus, the end of the last convolution I6a of conductor I6, has been provided with a tab 53. Likewise secured to the outer convolution Ilia, there is a member 54 provided with a tab 56. A connecting member 'I, of insulating material, is provided with a slot 58, through which the tabs 53 and 56 extend. Upon bending the tabs 53 and 56 as illustrated in Fig. 3, it is evident that the last convolution IBa is maintained tight about the main body of the coil, thus making the coil self-supporting, with all of the convolutions retained relatively tight upon each other. The terminal of the coil which has electrical connection with the outer convolutions IBa, is attached by soldering or welding, as indicated at 59.

The switch described above is useful in a variety of electrical circuits, particularly where it is desired to control closing of contacts in accordance with current flow to two separate appliances, from the same source of current supply. For example it can be used where an electrical heating range and an electrical hot water heater, are connected to operate from a three-line alternating current supply. The two coils I4 and I5 can be connected in series with two lines of the current supply, so that current flow through the same will vary according to either one or both of two groups of heating elements of the range. The heating element of the water heater can be connected to the third line of the current supply, and to one of the other lines. The contacts of the relay can be connected to control current flow to the winding of a heavy duty magnetic switch, with this switch in turn controlling current flow to the heating element of the electrical hot water heater. Thus when the range demand does not exceed a predetermined value, current flow can occur to the various heating elements of the electrical range, and also to the heating element of the electrical hot water heater. In the event the current flow to the heating elements of the electrical range is increased beyond a predetermined value, the contacts of the relay switch are closed, whereby the magnetic switch either greatly decreases the current flow to the hot water heater, or interrupts such current flow in entirety. When the current consumption is again decreased to a normal value the contacts of the relay are automatically opened, whereby the magnetic switch again re-establishes normal connections to the electrical hot water heater. Systems of this character in which a relay can be used to advantage, are employed in various instances where the power rate is based upon a peak load, which must not be exceeded. Under such conditions a system such as described, making use of my relay, makes it possible to take full advantage of the advantageous power rate, without however exceeding the maximum demand requirement.

As has been apparent from the preceding description, the relay which I provide is of relatively simple construction, and it can be adjusted to trip at various values, by changing the setting of shaft 4I. Such adjustments can be readily made, while the device is in use, and without disturbing the other parts of the apparatus.

Even when full load current flows through the coils I4 and I5, humming noise is at a minimum. This is because of the spring mounting of contact 5I, which tends to dampen out vibration. It will be noted that the moving parts of the relay, together with contacts 41, 48, 59 and 5|, are all assembled upon plate 25, which mounts the coil I5. Thus the relay is a complete device with only one coil, but if two current coils are desired, the second coil can be readily added in the manner described, Without however interfering with adjustments in the tension applied to spring 38, after fabrication.

I claim:

l. In a system of the character described, a pair of field coils disposed in spaced side-by-side relationship about a common axis, a rotatable shaft extending between said coils and substantially intersecting the axis of the same, a magnetic armature mounted upon said shaft and having portions extending within each of said coils, contacts adapted to be opened and closed by angular movement of the shaft, a spring serving to urge said shaft to rotate in one direction, and means including an adjustable member, accessible through the space between said coils, for varying the tension of said spring.

2. In an electric device of the type desired, a current coil, a plate secured to said coil and extending over one end of the same, a shaft journaled to said plate and extending at right angles to the axis of the coil, a magnetic armature secured to said shaft, a contact carried by said shaft, a contact carried by said plate and adapted to cooperate with the first named contact, spring means tending to rotate the shaft in a direction to open said contacts, and means also carried by said plate for adjusting the tension on said spring, the axis of said shaft being spaced laterally from the coil and the adjacent face of the end plate.

3. In an electric device of the type desired, a current coil, a plate secured to said coil and extending over one end of the same, a shaft journaled to said plate and extending at right angles to the axis of the coil, a magnetic armature secured to said shaft, a contact carried by said shaft, a contact carried by said plate and adapted to cooperate With the first named contact, spring means tending to rotate the shaft in a direction to open said contacts, means also carried by said plate for adjusting the tension on said spring, the axis of said shaft being spaced laterally from the coil and the adjacent face of the end plate, and means for mounting a second field coil in spaced parallel relationship to the first coil to act upon said armature in conjunction with the first coil.

ARTHUR J. KERCHER. 

